Westerland is the largest town on Sylt and the place most visitors arrive at — the trains from the mainland terminate here and the long promenade above the main beach is the island's busiest stretch. The town has the unmistakable atmosphere of a North Sea seaside resort: a casino, a domed concert hall on the seafront, glass-fronted Strandkorb shops, and a pedestrianised shopping street running back from the beach.
It is not the prettiest place on the island — much of it was rebuilt in functional 1960s style after wartime damage — but the beach is wide and fine, the boardwalk lively in summer, and the seafood at the harbour restaurants reliably good. Stay elsewhere if you can; use Westerland as a base for transport, dinner, and a night out.